How to drop unique index with entity framework code first migrations

问题

I'm using Entity Framework 5.0 with Code First migrations enabled.

I've added Unique key by using:

CreateIndex("dbo.Groups", "Name", true);

Now I want to remove existing Unique key with next migration's Down() method by using:

DropIndex("dbo.Groups", "Name");

However I get the message:

Cannot drop the index 'dbo.Groups.Name', because it does not exist or you do not have permission.

I'm using connection string that assumes I'm DBO. What else could be wrong?

回答1:

There is another answer to this:

DropIndex("dbo.Groups", new[]{"Name"});

There is an overload of DropIndex that takes column names, but it takes an array of them. So for a single column name you still have to wrap it in an array to get to the overload.

回答2:

Ok, I solved this on my own :)

Apparently I misused syntax for DropIndex. I assumed it takes name of column, but instead it takes name of index. This worked:

DropIndex("dbo.Groups", "IX_Name");

:)

Talking to myself 2013!

来源：https://stackoverflow.com/questions/16862208/how-to-drop-unique-index-with-entity-framework-code-first-migrations